Aortic aneurysms pose a significant medical problem for the general population. Aneurysms within the aorta presently affect between two and seven percent of the general population and the rate of incidence appears to be increasing. This form of atherosclerotic vascular disease (hardening of the arteries) is characterized by degeneration in the arterial wall in which the wall weakens and balloons outward by thinning. Until the affected artery is removed or bypassed, a patient with an aortic aneurysm must live with the threat of aortic aneurysm rupture and death.
One clinical approach for patients with an aortic aneurysm is aneurysm repair by endovascular grafting. Endovascular grafting involves the transluminal placement of a prosthetic arterial stent graft within the lumen of the artery. To prevent rupture of the aneurysm, a stent graft of tubular construction is introduced into the aneurysmal blood vessel, typically from a remote location through a catheter introduced into a major blood vessel in the leg.
When inserted and deployed in a vessel, a stent graft acts as a prosthesis to maintain and restrict blood flow through the vessel. The stent graft typically has the form of an open-ended tubular element and most frequently is configured to enable its expansion from an outside diameter which is sufficiently small to allow the stent graft to traverse the vessel to reach a site where it is to be deployed, to an outside diameter sufficiently large to engage the inner lining of the vessel for retention at the site.
The customary procedure is to install a stent graft to bypass the aneurysmal site. The stent graft is expanded to engage the inner lining or inwardly-facing surface of the vessel wall with sufficient resilience to allow some contraction from full expansion size of the stent graft but also with sufficient stiffness so that the stent graft largely resists the natural recoil of the vessel wall—particularly at the ends of the stent graft where it encounters and creates a sealing engagement with healthy vessel tissue.
Despite the effectiveness of endovascular grafting, once the aneurysmal site is bypassed, the aneurysm remains. The aortic tissue can continue to degenerate such that the aneurysm increases in size due to thinning of the medial connective tissue architecture of the aorta and loss of elastin. Further, damage or advancement of the aneurysm to the neck area of the vessel where the stent graft makes contact with the vessel wall (beneath the renal arteries) can result in leakage and/or migration of the stent graft.
The use of sclerotherapy to treat large varicose veins was first attempted over 150 years ago, making it the oldest therapeutic technique in the treatment of varicose veins. Recent years have provided technology that has increased understanding of the anatomy and physiology of this process, enhancing its success in a wide range of situations and leading to application of sclerotherapy in other therapeutic techniques.
Thus there is a desire in the art to achieve a greater success of aneurysm repair including stabilization of the vessel adjacent the stent graft.